Preventing javascript errors on "stopping" my code

You can use the window.onerror event handler as a global event handler and write something like:

window.onerror = function myErrorHandler(error, url, lineNumber) {
  logger("error has occured = " + error);
  return false;
}

you can read more about it here:

https://developer.mozilla.org/en-US/docs/Web/API/GlobalEventHandlers/onerror

If you just want to continue, there's try-catch-finally:

try {
  tryCode - Block of code to try
}
catch(err) {
  catchCode - Block of code to handle errors
}
finally {
  finallyCode - Block of code to be executed regardless of the try / catch result
}